The Emory University Division of Cardiothoracic Surgery, with its collaborators in allied specialties, seeks to establish a Clinical Center and contribute a Clinical Research Skills Development Core to the Network for Cardiothoracic Surgical Investigations in Cardiovascular Medicine (RFA-HL-06-005) in order to: 1) foster rigorous scientific evalution of newer surgical techniques and technologies, 2) build an infrastructure for multicenter collaborative clinical research directed at cardiovascular disease, 3) promulgate the use of evidence-based medicine and 4) serve as a clinical trials training ground in Cardiothoracic surgery. We propose two Model Protocols as examples of important questions in Cardiothoracic surgery that impact large adult populations, can be evaluated through small, short-term clinical studies and require the implementation of the Network to answer. Specifically, we hypothesize that patients with persistent or permanent atrial fibrillation (AF) and left atrial enlargement will have significantly greater freedom from AF 12 months after minimally invasive surgical ablation than after catheter ablation, measured by an autocapture continuous event monitor. In the second Model Protocol, we hypothesize that in patients with coronary artery disease (CAD) and moderate (2+-3+) ischemic mitral regurgitation (IMR), the incidence of major adverse cardiac events (MACE) 30 days after isolated CABG will be lower than after combined CABG with mitral valve surgery, and that the incidence of MACE 2 years after isolated CABG will not be higher than after combined CABG with mitral valve surgery. Each protocol incorporates a prospective, randomized controlled trial design and suggests numerous correlative science sub-studies. The Emory University Division of Cardiothoracic Surgery ranks in the top 1% of the nation for volume of open heart surgery performed annually and has the patient population, clinical research experience, infrastructure and enthusiastic collaborators in allied specialties to enroll large numbers of patients simultaneously into multiple clinical protocols within the proposed Network. We are committed to evidence-based practice in Cardiothoracic surgery and if chosen to become a Clinical Center, will adhere to all guidelines and regulations of the Network, including sharing of data and timely dissemination of findings to ensure that the public has access to the best procedures in Cardiothoracic surgery, determined by careful assessment.